The long range goal of this research is to increase the clinical efficacy of topical fluoride therapy of human enamel. Certain formulations of fluoride and surface active agents show evidence of accelerating deposition of firmly bound fluoride in enamel during enamel-fluoride interaction in vitro. Administration of fluoride in the drinking water in conjunction with those surfactants to rats and hamsters causes greater caries inhbition than administration of the individual agents. There is also preliminary evidence of an additive anticaries effect of repeated topical applications of such compositions to rodent teeth. A liquid formulation that gels in situ after application to the teeth has also been developed. Such gel systems formulated with neutral sodium fluoride impart more fluoride to enamal than their solution counterparts. The proposed research includes testing of the caries inhibitory effect in rodents of topical application of fluoride-surfactant formulations to the teeth. Specifically, it is proposed (1) to evaluate in rats and hamsters the caries inhibitory effect of frequently applied low concentration formulations or infrequently applied higher concentration formulations and (2) to study fluoride deposition in enamel in vitro from self-gelling systems formulated with acid fluoride compositions. The findings will have the potential of leading to formulation of fluoride mouthwashes, dentifrices and products for professional application that may offer increased caries protection or contain less ionic fluoride without losing their current efficacy.